SUBLETTE, Kansas (USA TODAY) – Just before 3 a.m., Jay Garetson’s phone buzzed on the bedside table. He picked it up and read the text: “Low Pressure Alert.”

He felt a jolt of stress and his chest tightened. He dreaded what that automated message probably meant: With the water table dropping, another well on his family’s farm was starting to suck air.

The Garetson family has been farming in the plains of southwestern Kansas for four generations, since 1902. Now they face a hard reality. The groundwater they depend on is disappearing. Their fields could wither. Their farm might not survive for the next generation.

At dawn, Jay was out among the cornfields at the well, trying to diagnose the problem. The pump was humming as it lifted water from nearly 600 feet underground. He turned a valve and let the cool water run into his cupped hands. Just as he had feared, he saw fine bubbles in the water.

“It’s showing signs of weakening,” he said sadly, standing in the shoulder-high corn.

“This’ll last another five or 10 years, but not even at the production rate that we’re at here today,” he said. “It’s just a question of how much time is left.”

Time is running out for portions of the High Plains Aquifer, which lies beneath eight states from South Dakota to Texas and is the lifeblood of one of the world’s most productive farming economies. The aquifer, also known as the Ogallala, makes possible about one-fifth of the country’s output of corn, wheat and cattle. But its levels have been rapidly declining, and with each passing year more wells are going dry.

As less water pours from wells, some farmers are adapting by switching to different crops. Others are shutting down their drained wells and trying to scratch out a living as dryland farmers, relying only on the rains.

In parts of western Kansas, the groundwater has already been exhausted and very little can be extracted for irrigation. In other areas, the remaining water could be mostly used up within a decade.

The severe depletion of the Ogallala Aquifer is symptomatic of a larger crisis in the United States and many parts of the world. Much more water is being pumped from the ground than can be naturally replenished, and groundwater levels are plummeting. It’s happening not only in the High Plains and drought-ravaged California but also in places from the Gulf Coastal Plain to the farmland of the Mississippi River Valley, and from the dry Southwest to the green Southeast.

In a nationwide examination of the problem, USA TODAY and The Desert Sun analyzed two decades of measurements from more than 32,000 wells and found water levels falling in nearly two-thirds of those wells, with heavy pumping causing major declines in many areas. The analysis of U.S. Geological Survey data revealed that:

Nationwide, water levels have declined in 64 percent of the wells included in the government database during the past two decades.

The average decline among decreasing wells has been more than 10 feet, and in some areas the water table has dropped more than 100 feet during that period – more than 5 feet per year.

For 13 counties in Texas, New Mexico, Mississippi, Kansas and Iowa, average water levels have decreased more than 40 feet since 1995.

Nationally, the average declines have been larger from 2011-2014 as drought has intensified in the West. But water tables have been falling consistently over the years through both wet and dry periods, and also in relatively wet states such as Florida and Maryland.

Across the High Plains, one of the country’s largest depletion zones, the average water levels in more than 4,000 wells are 13.2 feet lower today than they were in 1995. In the southern High Plains, water levels have plunged significantly more – in places over 100 feet in just 20 years. […]

That estimate of water losses from 1900 through 2008, calculated by USGS scientist Leonard Konikow, shows the High Plains has accounted for 35 percent of the country’s total depletion. California’s Central Valley accounted for more than 14 percent, and other parts of the country have depleted the remainder, about half of the total.

In places, water that seeped underground over tens of thousands of years is being pumped out before many fully appreciate the value of what’s lost. The declines in groundwater in the United States mirror similar decreases in many parts of the world. […]

The Kansas Geological Survey has mapped out how much longer the aquifer can support large-scale pumping. It projects that some places still probably have more than a century of water left, but that large patches of western Kansas will go dry in less than 25 years. Some areas will likely run out faster, within a matter of years. [more]